Currently, several commonly used methods in factoriesPrecision castingAll methods can meet actual production needs, but the performance indicators of the mold material are directly related to the quality of precision castings, directly affecting their dimensional accuracy and quality. Therefore, higher requirements must be placed on the dimensional and quality control of mold material castings. The performance requirements that the mold material needs to meet are as follows:
1. It should have a small linear shrinkage rate and a minimal coefficient of expansion within the softening temperature range to achieve the required dimensional accuracy of the mold material.
2. It has a small heat capacity and a moderate melting point, making it convenient to make molds from wax and remove wax from the molds.
3. The molding material should have sufficient hardness and strength at room temperature, and also high thermal stability at slightly above room temperature. This is to prevent various breakages, damages, or surface scratches in actual production and daily life.
4. Its low viscosity in the molten state gives it good flow properties and molding performance. This requirement is very important for thin-walled and complex-shaped castings, that is, it can fill the cavity well during injection and the mold material can flow out smoothly during demolding.
5. The molding material should have a fine grain structure, so as to have a smooth surface and good mold coverage.
6. Minimal residual ash content is required, meaning that after thorough calcination, the inner wall of the hollow mold shell should be almost free of other substances to prevent affecting the surface quality of the casting and other properties.
7. Low volatile content at low temperatures ensures the reusability of the molding material and facilitates recycling.
8. The molding compound should also have high chemical stability and good coating performance. It should not produce volatile harmful gases during the preparation process, and should have as little harm to the environment as possible. It should not react chemically with the coating surface, and the components of the molding compound should be readily available and inexpensive.
